#ifndef __PROCESS_POOL_HPP__
#define __PROCESS_POOL_HPP__

#include <iostream>
#include <cstdlib>
#include <vector>
#include <unistd.h>
#include <sys/wait.h>

#include "task.hpp"

//先描述
class Channel
{
    public:
    Channel(int fd, pid_t id)
    :_wfd(fd),
    _subid(id)
    {
        _name = "channel-" + std::to_string(_wfd) + "-" + std::to_string(_subid);
    }
    ~Channel()
    {}

    void send(int code)
    {
        int n = write(_wfd, &code, sizeof(code));
        (void)n;
    }

    void Close()
    {
        close(_wfd);
    }

    void Wait()
    {
        pid_t rid = waitpid(_subid, nullptr, 0);
        (void) rid;
    }

    std::string Name(){
        return _name;
    }
    int wfd() 
    {
        return _wfd;
    }

    ssize_t subid()
    {
        return _subid;
    }
    private:
    int _wfd;
    pid_t _subid;
    std::string _name;
};

//再组织
class ChannelManger
{
    public:
    ChannelManger()
    :_next(0)
    {}
    void Insert(int wfd, pid_t subid)
    {
        _channels.emplace_back(wfd, subid);
    }

    void PrintfChannel()
    {
        for(auto channel : _channels)
        {
            std::cout << channel.Name() << std::endl;
        }
    }
    //负载均衡
    Channel &Select()
    {
        auto &c = _channels[_next++];
        _next = _next % _channels.size();
        return c;
    }

    void CloseAll()
    {
        for(auto channel : _channels)
        {
            channel.Close();
            std::cout << "关闭" << channel.Name() << std::endl;
        }
    }

    void StopSubProcess()
    {
        for(auto channel : _channels)
        {
            channel.Close();
            std::cout << "关闭" << channel.Name() << std::endl;
        }
    }

    void WaitSubProcess()
    {
        for(auto channel : _channels)
        {
            //waitpid(channel.subid(), NULL, 0);
            channel.Wait();
            std::cout << "等待 回收" << channel.Name() << std::endl;  
        }
    }

    void CloseAndWait()
    {
        for(auto channel : _channels)
         {
             channel.Close();
             std::cout << "关闭" << channel.Name() << std::endl;
             //waitpid(channel.subid(), NULL, 0);
             channel.Wait();
             std::cout << "等待 回收" << channel.Name() << std::endl;  
         }

        // for(int i = _channels.size() - 1; i >= 0; i--)
        // {
        //     _channels[i].Close();
        //     std::cout << "关闭" << _channels[i].Name() << std::endl;
        //     _channels[i].Wait();
        //     std::cout << "等待 回收" << _channels[i].Name() << std::endl;  
        // }
    }


    
    ~ChannelManger()
    {}

    private:
    std::vector<Channel> _channels;
    int _next;
};



const int gdefaultnum = 5;
class ProcessPool
{
    public:
    ProcessPool(int num)
    :_process_num(num)
    {
        _tm.Register(PrintLog);
        _tm.Register(Download);
        _tm.Register(Upload);

    }

    void work(int rfd)
    {
        while(true)
        {
            int code = 0;
            ssize_t n = read(rfd, &code, sizeof(code));
            if(n > 0)
            {
                if(n != sizeof(code))
                {
                    continue;
                }
                std::cout << "子进程[" << getpid() << "]收到一个任务码" << code << std::endl;
                _tm.Execute(code);
            }
            else if(n == 0)
            {
                std::cout << "子进程退出" << std::endl;
                break;
            }
            else
            {
                std::cout << "读取错误" << std::endl;
                break;
            }
        }
    }

    bool Star()
    {
        for(int i = 0; i < _process_num; i++)
        {
            //1 创立管道
            int pipefd[2] = {0};
            int n = pipe(pipefd);
            if(n < 0) 
                return false;

            //2 创立子进程
            pid_t subid = fork();
            if(subid < 0)
            {
                return false;
            }
            else if(subid == 0)
            {
                //子进程
                //让子进程 关闭 自己继承下来的，他的哥哥进程的w端 关闭就行了
                _cm.CloseAll();

                // 3. 关闭不需要的文件描述符
                close(pipefd[1]);
                work(pipefd[0]);

                close(pipefd[0]);
                exit(0);
            }
            else{                
                close(pipefd[0]); // 写端：pipefd[1];
                _cm.Insert(pipefd[1], subid);
            }

        }
        return true;
    }

    void Debug()
    {
        _cm.PrintfChannel();
    }


    void Run()
    {
        //1 选择一个任务
        int taskcode = _tm.Code();

        // 2. 选择一个信道[子进程],负载均衡的选择一个子进程，完成任务
        auto &c = _cm.Select();
        std::cout << "选择了一个子进程: " << c.Name() << std::endl;

        // 2. 发送任务
        c.send(taskcode);
        std::cout << "发生了一个任务码" << taskcode << std::endl;
    }

    void Stop()
    {
        //关闭所有父进程 的 wfd
       // _cm.StopSubProcess();
        //关闭所有子进程 并回收
       // _cm.WaitSubProcess();
        _cm.CloseAndWait();
    }

    ~ProcessPool()
    {}
    private:
    ChannelManger _cm;
    int _process_num;
    TaskManger _tm;
};


#endif